1. Field of the Invention
The present invention relates to a process for testing the performance of a shock absorber by means of a shock absorber testing device.
2. Background Information
Shock absorbers are of great importance, not only for driving comfort, but also for driving safety. They must provide good road hugging ability of the wheels, and thus correct road holding characteristics of the vehicles. Good road holding characteristics can only be guaranteed when the vehicle is equipped with properly operating shock absorbers. Since the shock absorbers are constantly exposed to high stresses, they must also be checked after a certain period to make certain that they are still operating correctly.
The most precise method for testing the performance of shock absorbers is a measurement performed on a special test machine, of the type used by the Development and Quality Assurance Departments of companies in the motor vehicle industry. These machines can be used to check the overall damping force characteristics of a shock absorber. But these special machines are very expensive, and are therefore unprofitable to operate, even for large motor vehicle maintenance operations or dealers. Furthermore, the shock absorbers can also be tested on such a machine only after they have been removed from the vehicle.
Makeshift measures are frequently employed by mechanics, such as the rocking of the vehicle body or a test drive. But the ease with which these tests can be performed is offset by a significant risk of inaccuracy and uncertainty in the results.
One shock absorber testing device is disclosed in German Utility Model No. 93 03 201. On this shock absorber testing device, the condition of the individual shock absorbers is determined by means of a comparative measurement. The vehicle is parked with one vehicle axle on a wheel support which can be placed in oscillation. An unregulated drive unit in connection with a cam excites the wheel support to a supercritical oscillation frequency of approximately 15 Hz. The drive unit is then turned off, whereby the wheel support during the damped fading, or decay, movement automatically runs through the resonance range, making it possible to evaluate the condition of the shock absorber. In this test method, conclusions are drawn from the overall oscillating behavior of the chassis concerning the effectiveness of the shock absorber and the operating condition of the overall chassis.